JPH103186A - Electrostatic photographic printing machine, and monitoring/controlling method for electric parameter on image forming surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for monitoring/controlling the electric parameter of an image forming surface. SOLUTION: A monitoring/controlling device includes a patch generator for recording a first control patch at a first voltage level and a second control patch at a second voltage level, on the image forming surface and an electrostatic wattmeter for measuring potentials related to the first and second control patches. A processor cooperated with the patch generator calculates the electric parameter of the image forming surface from the potentials measured from the first and second control patches. The processor decides the deviation between the calculated electric parameter value and a set up value. When the deviation exceeds a threshold level, the processor generates a feedback error signal and transmits it to the patch generator. This patch generator receives the error signal, to record a third control patch at a third voltage level on the image forming surface. An ESV senses the third control patch and the processor calculates the electric parameter on the image forming surface from the measured parameter of the third control patch, to decide a correction factor. A charge device, an exposure system and a developer are adjusted according to the correction factor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates generally to electrostatographic print machines, and more particularly to a process control system preferably used in electrostatographic print machines.

[0002]

BACKGROUND OF THE INVENTION The basic copying method used in electrostatographic printing machines generally includes an initial step of charging the photoconductive member to a substantially uniform potential. The charged surface of the photoconductive member is then exposed to a light image of the document (document) to selectively dissipate the charge on the photoconductive member in selected areas illuminated by the light image. By this procedure, an electrostatic latent image corresponding to the information area included in the document to be copied is recorded on the photoconductive portion. The latent image is then developed by contacting the developer image with developer material containing toner particles electrostatically attached to the carrier particles. The toner particles separate from the carrier particles and are attracted to the latent image to form a toner image on the photoconductive member, which is transferred to a copy sheet. The copy sheet with the toner image is advanced to a fusing station where the toner image is permanently fixed to the copy sheet to form an image.

The method used for multicolor electrostatographic printing is almost identical to the method described above. However, rather than forming a single latent image on the photoconductive surface to copy the original as in black and white prints, multiple latent images corresponding to the color separations are printed on the photoconductive surface. Recorded continuously. The monochrome electrostatic latent image is developed with complementary toners, and the process is repeated for different color images using each complementary toner.
Thereafter, the single-color toner image is transferred to a copy sheet in superimposed registration with the previous toner image to form a multi-layer toner image on the copy sheet. Finally, the multi-layered toner image is permanently fixed to the copy sheet in a substantially conventional manner to form the final color copy.

[0004] In electrostatographic machines that use photoconductive members of the drum type or endless belt type, the photoreceptor (eg, photoreceptor) surface of the photoconductive members is exposed to various processing stations. As they pass, they may contain more than one image at a time. Projected image, so-called
The portions of the photosensitive surface that contain "image areas" or "pitches" are separated by segments of the photosensitive surface, commonly referred to as interdocument (ID) spaces. After charging the photoreceptor surface to a suitable charge level, the interdocument space segment on the photoreceptor surface is discharged by a suitable lamp to prevent toner particles from being attracted at the development station. Thus, various areas of the photoreceptor surface are charged to different voltage levels. For example, there is an initial charge at a high voltage level on the photoreceptor surface, there are image areas of the photoreceptor surface that are selectively discharged, and there are well-discharged photoreceptor surface portions between the image areas.

One type of photoconductive imaging member, a flexible photoreceptor belt, is typically multi-layered, comprising a substrate, a conductive layer, an optional hole blocking layer, an optional adhesive layer, a charge generating layer, It has a transport layer and, in some embodiments, an anti-curl backing layer or a protective overcoat. High speed electrophotographic copiers and printers use flexible photoreceptors to produce high quality toner images. Extended belt cycling results in reduced life levels and requires belt replacement to continue producing high quality toner images. As a result, the characteristics of the photoreceptor that affect the limit of the life of the photoreceptor and the image quality of the toner output image have been clarified. Photoreceptor properties that affect image quality include the following: charge acceptance upon contact with a given charge; dark decay in stopped (first cycle) and fatigued (steady state) conditions; function of light intensity Discharge or photo-induced discharge characteristics (PIDC), which is the relationship between the residual potentials; spectral response characteristics and residual potentials. As the photoreceptors age, they enter a state known as cycle up and cycle down. Cycle-up (residual rise) refers to residual potential and / or
Or, a phenomenon in which the background potential continues to increase as a function of the cycle and the density of the background in the copy of the document increases and becomes unacceptable. Cycle down is a phenomenon in which the dark development potential (the potential corresponding to the unexposed areas of the photoreceptor) continues to decrease as a function of the cycle as a result of dark decay, thereby reducing the image density of the document copy.

Various methods have been used to control the electrical parameters of the photoconductive surface to ensure high print quality. Many of the methods typically use one or more test patches (or sometimes also referred to as control patches) on the photoconductive surface of the intermediate zone, and electrical properties are measured on the intermediate zone by capacitively coupled probes. The photoreceptor will rotate for several cycles and, once a sufficient number of measurement points (ie, data) are obtained, measure the test patch at different electrical states (ie, charging potential and exposure) for each cycle. A process control algorithm in the control electronics uses the obtained data to predict a generalized average electrical characteristic of the entire photoreceptor. Secondly, the control electronics continuously adjusts the charging current and exposure range, so that the photoconductive surface has a normal development field.

[0007]

According to one aspect of the present invention, there is provided an apparatus for monitoring and controlling an electrical parameter of an imaging surface, the monitor and control device comprising a first voltage on the imaging surface. A patch generator for recording a first control patch of a level and a second control patch of a second voltage level; and an electrostatic voltmeter for measuring a potential associated with the first control patch and the second control patch. A processor cooperating with the patch generator calculates an electrical parameter of the imaging surface from the measured potential from the first and second control patches. The processor determines a deviation between the calculated electrical parameter value and the setup value. next,
If the deviation exceeds a threshold level, the processor generates a feedback error signal and sends it to the patch generator. A patch generator receives the error signal and records a third control patch at a third voltage level on the imaging surface. The ESV senses the third control patch. The processor calculates an electrical parameter of the imaging surface from the measured potential of the third control patch to determine a correction factor. The charging device, exposure system and developer are adjusted according to the correction factor.

According to a first aspect of the present invention, there is provided a charging device having an image forming surface moving in a processing direction along a preselected path, charging the image forming surface, an exposure system for recording a latent image, An electrostatographic print machine including a developer for developing the latent image and a device for monitoring and controlling electrical parameters of an imaging surface, wherein the monitoring and control device includes a first voltage level on the imaging surface. A patch generator for recording a first control patch and a second control patch of a second voltage level, wherein the first control patch and the second
An voltmeter arranged to measure a potential associated with a control patch, wherein the voltmeter cooperates with the patch generator and forms an image from the potential measured from the first and second control patches in response to the voltmeter. A processor for calculating electrical parameters of the surface, the processor determining a deviation between the calculated electrical parameter value and the setup value, and generating a feedback error signal if the deviation exceeds a threshold level; Sending to a patch generator, the patch generator recording a third control patch at a third voltage level on the imaging surface, and the voltmeter and the processor determining the electrical potential of the imaging surface from the measured potential of the third control patch. Calculate the parameters, determine the correction factor, and according to the correction factor, the charging device, the exposure system, and the developer. Having means for adjusting one even without.

According to a second aspect of the present invention, there is provided a charging device for charging an image forming surface, an exposure system for recording a latent image, and a developing device for developing the latent image. A method for monitoring and controlling an electrical parameter, comprising: a) recording a first control patch at a first voltage level and a second control patch at a second voltage level on an imaging surface; 1
Measuring a potential associated with the control patch and the second control patch; and c) calculating first and second electrical parameters of the imaging surface from the potential measured from the first and second control patches. D) determining a deviation between the calculated first and second electric parameter values, and e) generating a feedback error signal if the deviation exceeds a threshold level. F) recording a third control patch at a third voltage level on the imaging surface in response to the error signal; and g) sensing a potential associated with the third control patch. H) calculating a third electrical parameter of the imaging surface from the measured potential of the third control patch, and i) determining a correction factor based on the third electrical parameter. Comprising the step of, j) comprises the step of adjusting at least one of the charging device in accordance with the correction factor, exposure system and developer.

According to a third aspect of the present invention, in the second aspect, a step of determining a second deviation between the third electrical parameter and the preset target is provided.

[0011] Other features of the present invention will become apparent from the following description read in conjunction with the drawings.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS For a general understanding of the features of the present invention, reference is made to the drawings wherein like reference numerals are used to refer to like elements throughout. A schematic front view illustrating an exemplary electrophotographic print machine having features of the present invention is shown in FIG. It will be appreciated that the present invention is equally suitable for use in a wide range of printing systems, including ionographic print machines, discharge area development systems, and other more general non-printing systems that provide multiple or variable output. As will be apparent from the following description, the invention is not necessarily limited to the application to the particular systems set forth herein.

Referring first to FIG. 3, an exemplary electrostatographic copying machine will be described before describing in detail certain features of the present invention. Exemplary electrostatographic systems are described, for example, in Xerox Corporation.
Copier, such as the "5090" copier of US Pat. To start the copying process, the multicolor document 38 is placed on a raster input scanner (RIS) 10. R
IS 10 includes a document illumination lamp, optics, a mechanical scanning drive, and a charge coupled device (CCD array) that receives the entire image from document 38. The RIS 10 converts the image into a series of raster scan lines and measures a set of primary color densities, i.e., red, green and blue densities, at each point on the document. This information is communicated as electrical signals to an image processing system (IPS) 12, which converts the set of red, green, and blue density signals into a set of color coordinates. The IPS includes control electronics that regulates and manages the flow of image data to a raster output scanner (ROS) 16.

The user interface (UI) 14 is an IP
Provided for communicating with S. The UI 14 allows the operator to control various operator adjustable functions, and the operator operates the appropriate input keys on the UI 14 to adjust the copy parameters. UI 14 may be a touch screen or any other suitable device that provides an operator with an interface to the system.
An output signal from the UI 14 is transmitted to the IPS 12, and
The PS transmits a signal corresponding to a desired image to the ROS 16. ROS 16 includes a laser having a rotating polygon mirror block. ROS 16 illuminates the charged portion of photoconductive belt 20 of printer or marking engine 18 via mirror 37. Preferably, a multi-faceted polygon mirror is used to illuminate the photoreceptor belt 20 at a speed of about 400 pixels / inch. The ROS 16 exposes the photoconductive belt 20 to record a latent image on the belt corresponding to the signal transmitted from the IPS 12.

With continued reference to FIG. 3, the marking engine 18 is an electrostatographic print machine having a photoconductive belt 20 with seams 21 that includes transfer rollers 24, 26, pull rollers 28 and It is wrapped around the drive roller 30. Drive roller 30 is rotated by a motor or other suitable mechanism that couples to drive roller 30 by suitable means, such as a belt drive 32. As the roller 30 rotates, it advances the photoconductive belt 20 in the direction of arrow 22 so that various portions of the photoconductive belt 20 are disposed around the path of movement of the photoconductive belt. Forward to pass through. Photoconductive belt 2
O is preferably formed from a conductive material including an anti-curl layer, a support substrate layer and an electrostatographic imaging single layer or multiple layers. The imaging layer may include a homogeneous or heterogeneous inorganic or organic compound. It is preferable that finely divided particles of a photoconductive inorganic or organic compound are dispersed in an electrically insulating organic resin binder. Typical photoconductive particles include trigonal selenium, metal-free phthalocyanines, copper phthalocyanines, vanadyl phthalocyanines, hydroxygallium phthalocyanines, titanol phthalocyanines, quinacridones, 2,4-diamino-triazines and polynuclear aromatic quinines. Typical organic resin binders include polycarbonates, acrylate polymers, vinyl polymers, cellulose polymers, polyesters, polysiloxanes, polyamides, polyurethanes, epoxies, and the like, and copolymers of the above polymers.

First, a portion of photoconductive belt 20 passes through charging station A. At charging station A, a corona generating device 34 or other charging device generates a charging voltage to charge photoconductive belt 20 to a relatively high, substantially uniform potential. The corona generating device 34 includes a corona generating electrode, a shield partially surrounding the electrode, and a grid disposed between the belt 20 and the unenclosed electrode portion. The electrodes charge the photoconductive surface of belt 20 via corona discharge. The potential applied to the photoconductive surface of belt 20 is varied by controlling the potential of the wire grid.

Next, the charged photoconductive surface rotates to exposure station B. Exposure station B receives a modulated light beam corresponding to the information derived by RIS 10 with document 38 placed thereon. The modulated light beam impinges on the surface of photoconductive belt 20 and selectively irradiates the charged surface of photoconductive belt 20 to form an electrostatic latent image on the surface.

After the electrostatic latent image has been recorded on photoconductive belt 20, the belt advances to developing station C. However, before reaching the development station C, the photoconductive belt 20 has a voltage monitor, preferably an electrostatic voltmeter 3.
3 and the potential of the surface of the photoconductive belt 20 is measured. The electrostatic voltmeter 33 is of any suitable type known in the art such that the charge on the photoconductive surface of the belt 20 is sensed, for example, US Pat.
No. 70,968; No. 4,205,257 or No. 4,8
No. 53,639, the contents of which are incorporated herein by reference.

A typical electrostatic voltmeter is controlled by a switching device, which provides a measurement condition in which a charge is induced on the probe electrode in response to the sensed voltage level of the control patch on belt 20. The induced charge is proportional to the capacitance between the probe and the measurement surface, plus the internal capacitance of the probe and associated circuitry and probe. The DC measurement circuit couples to the electrostatic voltmeter circuit to provide an output that can be read by an input to a conventional test meter or control circuit. As will be understood by reference to the subject matter of the invention described in detail below, the potential measurement of photoconductive belt 20 determines a particular parameter for maintaining a given potential on the photoreceptor surface. Used to

The developing station C includes a developer unit 40
including. This type of developer unit is the type commonly referred to in the art as a "magnetic brush developing unit". Typically, magnetic brush development systems use magnetic developer materials, including magnetic carrier granules having electrostatically attached toner particles. The developer material is continuously conveyed through the directional flux field to form a brush of developer material. The developer material is constantly moving to continuously provide a brush with new developer material. Development is accomplished by contacting a brush of developer material with the photoconductive surface.

The developer unit 40 applies toner particles to the electrostatic latent image recorded on the photoconductive surface.

After development, the toner image moves to transfer station D. Transfer station D includes a transfer zone 64, which defines the location where the toner image is transferred to a sheet of support material, which is plain paper or other suitable support substrate. The sheet conveying device 48 moves the sheet to make contact with the photoconductive belt 20. The sheet transport 48 has a belt 54 wrapped around a pair of generally cylindrical rollers 50 and 52.
The friction retard feeder 58 advances the uppermost sheet from the stack 56 to the pre-transfer transport 60,
The pretransfer transport advances the sheet to the sheet transport 48 in synchronization with the operation of the sheet transport, so that the leading edge of the sheet is at a preselected position,
That is, it reaches the loading zone. The sheet is received by the sheet conveying device 48 and moves along its circulation path. When the belt 54 of the transport device 48 moves in the direction of arrow 62, the sheet moves in synchronization with the toner image developed on the photoconductive belt 20 and comes into contact with the belt.

In the transfer zone 64, the corona generating device 66 ejects ions to the back of the sheet so that the sheet is charged to the appropriate size and polarity to attract the toner image from the photoconductive belt 20 to the sheet.

After the transfer operation, the sheet transport system directs the sheet to the vacuum conveyor 68. Vacuum conveyor 68 transports the sheet to fusing station E in the direction of arrow 70, where the transferred toner image is permanently fused to the sheet. The fusing station includes a heated fuser roll 74 and a pressure roll 72. The sheet passes through a nip defined by a fuser roll 74 and a pressure roll 72. The toner image contacts the fuser roll 74 and is fixed on the sheet.
Thereafter, the sheet is advanced to the catch tray 78 by the pair of rolls 76 and is continuously removed by the machine operator. The last processing station in the direction of belt 20 movement indicated by arrow 22 is cleaning station F. Lamp 80 illuminates the surface of the photoconductive belt to remove any residual charge remaining on the belt. A rotatably mounted fiber brush 82 is located at the cleaning station and removes residual toner particles from the transfer operation prior to the start of the next successive imaging cycle while contacting photoconductive belt 20.

The above description is sufficient for the purposes of this application to illustrate the general operation of an electrostatographic print machine that includes the features of this invention. As mentioned, the electrostatographic printing system may take the form of several known devices or systems. Certain electrostatographic processing subsystems or process variations are envisioned without affecting the operation of the present invention.

The concept of the present invention is a PIDC controller. In essence, a PIDC controller is a run-time control algorithm designed to maintain optimal xerographic performance over the life of the photoreceptor. Problems with residual rise and photoreceptor variability over life are alleviated by the present invention. Briefly, a plurality of control patches are generated during a normal copy, and these patches are then used to monitor the current state of the photoreceptor. This information includes V _ddp (high charge potential), V
It is used to determine the adjustment of conditions such as _bkg (background charge potential) and V _AMCal (exposure level charge potential analysis mode). The role these patches play in maintaining optimal performance is briefly described below.

As noted, the present invention uses the following control patch ESV readings ( _Vddp and _Vbkg ) as two input values, which patches are updated approximately once every photoreceptor cycle. ing. Once these readings are obtained, the next step is to increase the contrast (V _ddp −V
_bkg ) and the cleaning fields of rolls 1 and 2 (V _{bias rolls 1 & 2} - _Vbkg ). The deviation or error from the set point for each of the high contrast and roll 1 and 2 cleaning fields described above is: (V _{HC Error
= | [V ddp -V bk g} ] -V HC SetPt |.) And (V
_{cln 1 & 2 Error = | [} V bias rools 1 & 2 -V bk g] -V
_{cln 1 & 2 SetPt.} |). The setpoints or target values mentioned above are used in the error calculation. If no error is detected, the present invention continues this polling procedure until an error is found.

If the error present is a high contrast greater than the ESV bit (1 ESV bit = 5.88 volts) or a roll 1 & 2 cleaning field greater than the ESV bit, an AMCal patch is required and introduced into the above patch sequence. Is done. In other words, if an error in either the cleaning field or the high contrast is detected above the threshold, the new patch sequence is described above (V _ddp , V
_bkg ) substantially (V _ddp , V _bkg , V _{AM Cal} )
Becomes This new three patch sequence is repeated until convergence is obtained.

When the V _AMCal patch is read through the ESV, the low contrast error is calculated similarly (V
_{LC Error = | [V AMCal -V} bkg] -V
_{LC Setpt.} |). All three errors (V _{HC Error} , V
_{Once the LC error} and V _{cln 1 & 2 Error} are calculated, the present invention requires that any suitable value of V _ddp , exposure and bias voltage for rolls 1, 2 and 3 be used to minimize all errors simultaneously. Predict if there is. This procedure has an error of V
Reduced to 2 ESV bits for _{HC Error} , V
_{For cln 1 & 2 Error} , it is repeated until convergence is obtained, which means that it has been reduced to ₁ ESV bit, and then V
_{The AMCal} patch ends and the routine poll segment resumes control. This process is invoked immediately after cycle up, but before printing is enabled and ends with cycle down.

With the concept and principles of the present invention in mind, reference can now be made to the following computer pseudo-codes, FIGS. 1 and 2, to provide a complete understanding of the present invention.
It is assumed that the computer pseudo codes of outer 1 to outer 4 are continuous.)

[0031]

[Outside 1]

[0032]

[Outside 2]

[0033]

[Outside 3]

[0034]

[Outside 4]

In summary, the PIDC controller provides
And the normal runtime in the controller
Two patches are ESV (electrostatic voltmeter) during machine control
Monitored by V_ddp(The patch generator is
To the voltage required for toner control.
Closed loop control of charging and toner control when pressure is reduced
Values used for control) and V_bg(E_OAnd V_ddpof
Current level for background voltage relative to current value
Used to calculate) is monitored. roll
In addition to the current bias set points of 1, 2, and 3
Using these values, high contrast and cleaning
The field error is the target in NVM (non-volatile memory).
Calculated from the set value. High contrast is (V_ddpVoltage
Value-V_bgVoltage value). cleaning
The field is that of the developer bias setpoint voltage value.
V from each_bgCalculated by subtracting the voltage value
You. Either of these errors exceeds the threshold in NVM.
Algorithm, the intermediate exposure patch (V
_AMCal) Is required. Intermediate with this patch
An error is also calculated for the contrast target.
The intermediate contrast is (V _AMCalVoltage value -V_bgVoltage value) and
Is defined as Therefore, high contrast, medium
(Low) For contrast and cleaning fields
A gain value is derived from the calculated error value,
This gain value is high contrast, medium (low) contra
Targets with specified cleaning and cleaning fields
V to be modified to return to₀, E₀And vias
This is used to determine the correction amount for the error. V
_AMCalPatch generation depends on contrast target and clear
Both convergence field targets
And then V_{AMCa l}Patch generation stopped
Stopped, V_ddpAnd V_bgOnly patches regulate the system
Detect further deviations. The current patch scheduler is 2,
Two new patches (V
_bgAnd V_AMCalIt is used for the additional modification of). control
The patch is I. D. Generated in zones 2, 4 and 6
Will remain.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a series of processes used in the PIDC controller of the present invention.

FIG. 2 is a plan view of a control patch on the photoconductive belt of FIG. 1;

FIG. 3 is a schematic front view of an exemplary electrostatographic print machine that includes features of the present invention.

[Explanation of symbols]

 Reference Signs List A charging station B exposure station C developing station 18 marking engine 20 photoconductive belt 33 electrostatic voltmeter

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Barbara Sampath United States 14454 Geneseo West Lake Road, New York 629 (72) Inventor Lacey. Lamb USA 14580 New York Webster Gasbury Lane 731 (72) Inventor Patrick O. Waller United States 14619 Rochester Hillendale Street, New York 57 (72) Inventor Joseph A. Mastlandrea United States 14580 New York Webster Hartsville Lane 288

Claims (3)

[Claims] An image forming surface that moves in a processing direction along a preselected path, a charging device that charges the image forming surface, an exposure system that records a latent image, and a developer that develops the latent image And an apparatus for monitoring and controlling electrical parameters of the imaging surface, the monitoring and control device comprising: a first control patch of a first voltage level and a second voltage level on the imaging surface. A patch generator for recording a second control patch of the first control patch and a voltmeter arranged to measure a potential associated with the first control patch and the second control patch; A processor responsive to a voltmeter for calculating electrical parameters of an imaging surface from potentials measured from the first and second control patches, the processor comprising Determining a deviation between the measured electrical parameter value and the set-up value, and if the deviation exceeds a threshold level, generates a feedback error signal and sends it to the patch generator. Recording a third control patch of a voltage level, the voltmeter, the processor calculating electrical parameters of the imaging surface from the measured potential of the third control patch, determining a correction factor, and charging the device according to the correction factor. An electrostatographic print machine comprising means for adjusting at least one of an exposure system and a developer. 2. A charging device for charging an image forming surface,
An exposure system for recording a latent image, a method for monitoring and controlling electrical parameters of an imaging surface in an electrostatographic print machine having a developer for developing the latent image, comprising: a) a first voltage on the imaging surface; Recording a first control patch at a level and a second control patch at a second voltage level; b) measuring a potential associated with the first control patch and the second control patch; c) Calculating first and second electrical parameters of the imaging surface from potentials measured from the first and second control patches; and d) calculating the first and second electrical parameter values. E) generating a feedback error signal if said deviation exceeds a threshold level; and f) responding to the error signal. Recording a third control patch of a third voltage level on the imaging surface, and g) sensing a potential associated with the third control patch; and h) detecting a potential of the third control patch. Calculating a third electrical parameter of the imaging surface from the measured potential; i) determining a correction factor based on the third electrical parameter; j) a charging device, an exposure system according to the correction factor. And controlling at least one of the developer and a method for monitoring and controlling electrical parameters of the imaging surface. 3. The method of claim 2, comprising determining a second deviation between the third electrical parameter and the preset target.